Rotary Solenoids of this type are drives basing on the electro magnetic principle where, instead of a longitudinal motion, the result is a rotary motion. Rotary Solenoids of this kind are known, for example, as rotary proportional solenoids carrying out a rotary motion proportional to the current flow because of the current flow through the windings.
In the state of the art it is known not to realize a magnetic field arrangement rotational symmetric with respect to the rotational axis, but one asymmetric to it, if possible. This heterogeneously asymmetric magnetic field then interacts with the magnetized rotor disc. This magnetic field is generated by coils flown through by electric current. The different arrangement of north and south poles on the rotor disc (this is polarized magnetically alternating) then tries to be positioned appropriately in the generated magnetic field of the solenoid, that means to move or rotate.
In the state of the art it is known for that to arrange two or more rather complex coil forms in the stator to achieve the desired distribution of the flow of the magnetic field lines.
This is reached by an arrangement of several coils that have to be winded rather complicatedly around the rotational axis; that means the respective point of gravity of the coil is not on the rotational axis.
The result of this construction are rather expensively produced Rotary Solenoids as the single coils cannot be winded up on cylinder-shaped coil forms, but special forms, which have to be covered with wire windings, are required here that have to be provided, if necessary, also by using special production methods that are correspondingly expensive. Thus, each single coil has to be produced rather expensive, and also a rather large amount of coils has to be supplied arranged spaced apart from the rotational axis to result in an appropriate distribution of the magnetic field lines. Besides the high manufacturing costs, these suggestions according to the state of the art also have a rather large constructive space.